The present Invention relates to the field of control and motorization systems. More particularly, the present Invention relates to novel and improved control and motorization systems for window shades, blinds, and other window treatments (collectively xe2x80x9cwindow shade(s)xe2x80x9d or xe2x80x9cshade(s)xe2x80x9d) and other applications where control and motorization of a member is desired.
The field of window shades has undergone constant change. Changes have varied from manually operated shades to shades that are operated by remote control and by other means.
In spite of these changes, the field typically does not draw from unrelated fields that may have application in the window shade field. One such unrelated field is that of torque sensing. Although the diverse field of torque sensing has existed for some time, it has not been applied to the window shade field, at least until the issuance of U.S. Pat. No. 6,116,320, the entire contents of which is hereby incorporated herein by reference. That application relates to window shade operation that moves a shade usually up and down between top and bottom or open and closed positions. It also discloses aspects that can be applied generally to window shade applications and in other applications as well.
One basic way to open or close a window shade is to manually pull or release a lift cord that draws the shade up or down to a desired position while engaging a locking mechanism to prevent the shade from falling down. This manual lift system has been used for decades with lift cord applications until motorized window shade systems were introduced into the market. The introduction of motorization led to the need to develop newer types of lift systems that would allow for motor control or a mechanical clutch.
Motorized control systems are used frequently to advance objects between one or more positions. In addition, such control systems are important to control or cut off movement of a moving object upon reaching a selected position or upon sensing an obstruction so that the object is not damaged after the position or obstruction is reached. This problem is typified by the operation of window shades, where the shade is normally intended to advance between upper and lower, or open and closed, positions but often may encounter unexpected interference or obstructions in its path of travel. Unless the movement is timely stopped, damage may occur to one or more of the shade, drive system, and the power source.
Different approaches have been taken to solving this problem, such as by counting the number of revolutions between the end limits of travel of the shade, using limit switches at opposite end limits, as well as by using magnetic and piezoelectric motion sensors. Newer aspects of the prior art may involve a form of position monitoring, for example, using slotted disks with an optical circuit that counts pulses. In some existing approaches, although the top and bottom positions may be set using the position monitoring method, over time, progressive error builds up in the number of pulse counts related to position. This may occur, for example, due to rounding error, such that each time the shade is opened or closed, a small difference is perpetuated between the actual position of the moving rail and the position understood by the control. Consequently, over time, the shut-off position changes from the desired position, requiring continuous adjustment by the operator.
Other systems have a mechanical adjustment in the system to set the upper and lower limits. The endpoints have a mechanical limit switch to shut off the motor or a locking mechanism that uses electronic means to shut off the motor by current sensing characteristics. The problem with these options in recognizing endpoints is that there is a limit of the number of output rotations from the motor, which limits the size of the shade.
Another problem with the prior art is the inability to recognize obstructions in the shade""s motion. If the moving rail runs into an obstruction on the way up, current sensing electronics may stop the motor before the cord breaks or the motor is in lock rotor. On the way down, however, the shade will continue to unwind the lift cords even if the moving rail is not moving.
Some aspects of the prior art use speed sensing to control motor operation. However, problems persist in those systems. For example, some of those systems require a constant tension in lift cords, thus limiting the use of those systems in many applications. In addition, speed sensing systems are limited in their utility in particular types of movement, for example, they have limited utility in controlling or shutting off movement during the downward movement of a member, or when the member has reached its full limit of downward travel.
In addition, although some control systems for motorized shades may include control by operation of handheld remote control transmitter or by wall switch, none of the prior art provides a system for operation of a motorized shade in the absence of the remote control or wall switch, for example, by touching the shade to operate it.
None of the prior art approaches solves these problems by sensing the change in torque of the drive system generated in correlation with the travel of the shade. Thus, there remains a need for a system for determining the shut-off point in a shade, such that any deviation from the desired shut-off point is minimized or reduced. There also remains a need for a system to operate a motorized shade by touch control.
The present Invention comprises a novel and improved system for effecting and controlling the movement of a member between different positions, by way of example only, for opening and closing window shades. The present Invention comprises a novel lift system for window shades and any other application where movement of a member is desired. In particular, and without limitation, the Invention comprises a novel method to recognize and respond to obstructions in lift cord applications for motorizing lift products, as well as to provide touch control of the lift system.
In one preferred embodiment, the present Invention accomplishes shade movement by using an automated electrical device in concert with a spring-assisted motor. Thus, the operator can lift or touch the bottom of a moving rail but without lifting the entire weight of the shade due to the counterbalance in the spring mechanism. The movement imparted by the operator to the shade is sensed by the spring mechanism and a signal is sent to the motor controller, causing the motor to engage which lifts the shade by its own operation, as well as in conjunction with a spring-loaded device that counterbalances the shade.
The present Invention comprises mechanical and electrical components that, by way of example only, may fit inside the head rail of a shade and recognize an obstruction during the shade""s upward and downward path of travel.
The Invention also comprises a novel system to manually activate the shade. The touch control switch mechanism of the Invention itself includes an electronic mechanism to turn on and off, or raise a shade, by touch or pulling on it. Rather than wiring a wall switch or having a button on the head rail, the Invention allows the user to manually manipulate the moving rail, for example, by tugging, to operate the shade. This feature alleviates wiring difficulties for switch controls or for reaching head rail buttons on high shade locations, and operating difficulties caused by the absence of a handheld remote control. The Invention cures the problem by allowing the operator to pull or lift on the moving rail, which activates the shade to stop or to move in the opposite direction as it previously used. The Invention is particularly useful in situations where the end user needs privacy by closing the shade, the head rail is in a high difficult-to-reach location, and the remote control transmitter cannot be found.